1. Field of the Invention
The present invention relates generally to tools and devices for cleaning and maintaining equipment and particularly to a chemical pigging apparatus for pipelines.
2. Description of the Related Art
Practically all fluids, e.g. gas and oil, include various contaminants and materials that eventually fall out of solution or react with other materials. This is a particular problem in oil and gas pipelines and related conduits, as the contaminants and solids can include, for example, heavy organic materials such as asphaltenes, asphaltogenic acids, diamondoids, paraffins/wax, and resins, which exist in crude oils and tend to build up along the inner walls of the pipes. If this condition is left to continue for a sufficiently long time, the buildup of contaminants can reach such a thickness that the inner diameter of the pipe becomes significantly restricted, thus reducing fluid flow and efficiency of the pipe. The deposition of these suspended particles, therefore, severely inhibits the production and transportation of petroleum fluids. Moreover, such buildups almost always also results in uneven buildups within the pipes, thus creating turbulence and hydrodynamic or aerodynamic drag or resistance to the flow of materials through the pipes.
Accordingly, various systems have been developed in the past for cleaning such residue and deposits from the interior wall surfaces of pipes. Many, if not most, of these systems include remotely controlled or automated “pigs,” i.e., devices that conform to the interior of the pipe and travel the pipe to accomplish their intended purpose automatically. These pipeline pigs that are adapted or configured for cleaning out the pipes generally use some form of physical action to remove the buildup within the pipes, such as mechanical scrapers or high pressure blasting with liquids and/or particulates.
However, such scrapers and automatic pigs typically do not have the ability to break up and dissolve the deposits and residues that remain in the pipes, particularly in the receiving end of the pipeline, after the interior wall surfaces of the pipes are cleaned. This can make the process of extracting the scraper and cleaning the pig relatively hazardous and dangerous.
Thus, a chemical pigging apparatus addressing the aforementioned problem is desired.